Switched-mode power converters are used in a wide variety of electronic applications from simple consumer electronic applications such as power supplies for cellular phone chargers and personal computers, to industrial applications such as providing regulated power to heavy machinery. Because of their potential for achieving high levels of efficiency, switched mode power converters are also used in electric vehicles and hybrid electric vehicles to convert power between high voltage battery systems and lower voltage 12 V or 48 V supply systems. One of the requirements of such a switched-mode power converter is the ability to provide output power from a wide range of input voltages. For example, a typical electric car battery system may provide output voltages of between about 200 V and about 450 V depending on the state of charge of the battery system.
Designing a switched-mode power converter with a wide range of input voltages poses a number of challenges. One of these challenges is maintaining efficient operation over a wide range of input voltage, since many switched-mode power converter architectures have a peak efficiency over a narrow range of input voltages. One way of addressing the issue of a wide input voltage range is to provide a pre-regulator coupled between the widely variable battery voltage and the switched-mode power converter. This pre-regulator may, itself, be a switched-mode power converter.